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Relation of Temperature to the 

Growth and Infecting Power 

of Fusarium Lini 



W. H. TISDALE 



^IM 



Reprinted from Phytoi-athology, Vol. VIF, No. 5, 
October, 1917 



Reprinted from Phytopathologv, Vol. VII, No. 5, October, 1917 



RELATION OF TEMPERATURE TO THE GROWTH AND 
INFECTING POWER OF FUSARIUM LINI 

\V. H. T I S D A L E 

With Plate XI and One Figure in the Text 

Studies on the nature and inlieritance of resistance in flax to the wilt dis- 
ease, caused by Fitsarium Lini Bolley, were begun with the departments 
of plant pathology and experimental breeding of the University of Wiscon- 
sin in the winter of 1914-15. While growing plants in the greenhouse for 
these breeding experiments in the winter of 1915-16 the writer noted that 
marked differences existed in the rate of wilting of susceptible flax plants 
which were growing at different distances from the heating system. These 
observations, combined with temperature records, suggested the possi- 
bility that soil temperature might be one of the chief factors influencing 
the rate of infection of these plants. In order to determine this point 
experiments were arranged so that both the relation of temperature to the 
growth of the fungus in pure culture, and the relation of soil temperature 
to the infection of susceptiljle flax plants might be studied.' 

RELATION OF TEMPERATURE TO THE GROWTH OF THE FUNGUS IN CULTURE 

After ascertaining by careful measurement that actual correlation ex- 
isted between soil temperatures and the rate of wilting of the flax plants, 
a study was undertaken of the relation of the fungus to various tempera- 
tures while growing in pure culture on artificial media. An investigation 
of tliis kind was considered of fundamental importance in order to work 
out and understand thoroughly the relation of soil temperature to infec- 
tion. By using an mcomplete series of temperatures ranging from to 
37°C. it was found that the organism failed to grow below 10°C. and at or 
above 37°C. This preliminary experiment showed approximatelj^ the 
temperature limits of the fungus and gave some indications as to what 
temperatures were best suited for its growth. Another experunent was 
arranged, using a more complete series of temperatures, in which plates 

' The writer wishes to express his hearty appreciation to Professor H. L. Bolley 
of the North Dakota Agricultural Experiment Station for supplying flax seed and 
fiax sick soil for the work. He is also indebted to Professor L. R. Jones of the Uni- 
versity of Wisconsin for invaluable suggestions and kindly criticisms of the work as 
it progressed. 



ma 

TbeUuivarsttj 



1917] 



Tisdale: Temperature Relation 



357 



poured with a 1.8 per cent potato agar and inoculated in the center with 
bits of mycelium were incubated in duplicates at diiferent temperatures 
for six days. After incubation the colony diameters were measured 
(table 1) and the plates arranged in a temperature series and photographed 
(plate XI). The plate numbers in table 1 correspond to the numbers in 
the photograph. 

table I 

The effect of temperature on the growth of Fusarium Lini. Cultures six days old 



PLATE NO. 


TEMPERATURE 


m..METER or COLON. 




°c. 


mm. 


1 


8.5-10 





2 


11 


7 


3 


12-13 


20 


4 


14 


25 


5 


15 


29 


6 


16 


34 


7 


17 


38 


8 


19 


43 


9 


22 


68 


10 


24-25 


70 


n 


25-26 


72 


12 


26-28 


78 


13 


29-30 


75 


14 


34 


17 


15 


37 






It appears from table 1 that the minimum temperature for growth of 
the fungus lies between 10° and 11°C., the optimum at about 26° to 28°C., 
and the maximum between 34° and 37°C. Another set of experiments 
showed that the fungus is able to grow slightly at a temperature ranging 
from 35° to 36°C. Judging from the vigor of the fungus at the various 
temperatures, it would be expected that flax plants would wilt more 
readily with soil temperatures between 20° and 30°C. This was actually 
found to be the case with susceptible plants growing in the greenhouse. 



relation of soil temperature to infection- 

Wliile growing flax plants in the greenhouse for breeding experiments in 
the winter of 1915-16, as previously stated, a series of flats was placed 
near a system of heating pipes, wliile others were placed at a greater dis- 
tance from the pipes where the temperature was lower. A more rapid 

- Tisdale, W. H. Relation of soil temperature to the infection of flax b.y Fusarium 
Lini Boll. (Abst.) Phytopath 6: 412. 1916. 



358 Phytopathology [Vol. 7 

wilting of susceptilile plants was noticed in flats near the heating system. 
Soil temperatures were taken and it was found that the temperature in 
flats near the heating pipes ran at 18° to 20°C., while the temperature in 
flats farther from these pipes, where there was much less infection, ran 
at 14° to 17°C. This seemed to indicate that the critical temperature for 
the infection of flax by Fusarium Ldni is somewhat below 17°C., which 
was of the more interest, in view of the fact that Gihnan found that the 
lowest temperature for the infection of cabbage by Fusarium conglutinans 
Wr. is about 17°C. 

Following these observations an attempt was made by controlling the 
soil temperature to determine more accurately the lowest temperature for 
infection of flax by Fusarium Lini. The first attempt was made by plac- 
ing pots of infected soil containing germinating flax seeds in the cold- 
storage cellar near a small window where they could get light. Other 
pots planted at the same time were kept in the greenhouse as controls. 
The temperature in the cellar often ran below 10°C. during the nights. 
This temperature was too low for the plants to remain in a vigorous con- 
dition. The plants in the control pots began wilting in ten days and 
nineteen of the twenty-two plants were wilted at the end of twentj'-two 
days, whereas none of the plants at the lower temperature in the cellar 
had wilted. The experiment was then terminated by a sudden drop in 
temperature wlrich froze the plants in the cellar. 

A second attempt was made at controlling the soil temperature by ar- 
ranging a cool, circulating water jacket (fig. 1). A six-inch earthenware 
jar was filled about three-fourths full of infected soil and susceptible 
flax seeds planted. This jar was then supported in a larger jar, through 
which cold water flowed continuously, as shown in the figure. Seeds were 
planted in a similar jar and placed nearby at greenhouse temperature as 
a control. At the time these experiments were begun the temperature of 
the water was about 9°C. By careful regulation of the flow by means of 
the faucet valve it was possible to hold a fairly constant temperature be- 
tween this point and the greenhouse temperature. A temperature rang- 
ing between 12° and 15°e. was maintained for eight days and the plants 
remained free from infection. The temperature was then raised to \<6° to 
17°C. for two days and lowered again to 12° to 15°C. Four of the twenty- 
three plants in the jar showed signs of the wilt within two days even at 
these low temperatures. Infection evidently occurred during the brief 
period at the higher temperature. The small earthenware jar was found 
to be unsatisfactory due to the fact that the material allowed too much 
condensation or seepage which kept the soil almost saturated. The ex- 
periment was then repeated with a glass battery jar substituted for the 
earthenware jar. The glass jar proved more satisfactory. In the second 



1917] 



Tisdale: Temperature Relation 



359 



experiment it was found that at temperatures below 15°C. no wilting of 
flax plants occurred, while plants in the control pot at temperatures rang- 
ing from 19° to 21°C. wilted rapidly. During the earlier part of this trial 
when the temperature was held at 13° to 14°C. the flax plants grew fairly- 
well and no indications whatever of wilt were evident (fig. 1, A). After 
one month, when the temperature had risen to 15°C. only one plant of the 
twenty-one in the cold jar showed any sign of infection, while all of the 
thirty-three plants in the control jar were killed by wilt. The temperature 
in the cold jar could not be lowered as the water was warming up with the 
coming spring. 




Fig. 1. Relation of Temperature to the Infection of Flax by F. Lixi 

A, Susceptible flax plants growing at 13° to 15°C. in infected soil in a glass jar 
surrounded by running water. The smaller jar is supported by a glass tumbler in- 
verted on the bottom of the larger jar. B. Susceptible plants growing in infected 
soil at greenhouse temperatures (19°-21°C.). Plants in this jar are practically all 
dead with wilt. 

It seems from these experiments that the critical temperature for in- 
fect'on of flax by Fusariuni Lini is between 14° and 16°C. This conclusion 
accords well with the previous evidence secured by culturing the fungus 
on agar at graduated temperatures. As stated in table 1 the minimum 
temperature was found to be 10° to 11°C. and reference to plate I will show 
that but little growth occurred below 15°C. We should expect the critical 
temperature for infection to be somewhat higher than the minimum tem- 



360 Phytopathology [1917 

perature at which the parasite will grow, especially since the host plant 
thrives well at the lower temperatures. In this case it seems clear that 
the host plant which is susceptible at the higher temperatures is able to 
resist or overcome whatever weak attempts at invasion the fungus can 
make at the lower temperatures. 

The evidence here presented supplementing that secured by Oilman^ 
should at least warrant further careful attention to the relation of tem- 
peratiu^es to infection with the soil parasites, and especially the species 
of Fusarium. 

CONCLUSIONS 

1. Fusarium Lini grows on culture media at temperatures between 10'^ 
and 37°C., with its optunum temperature at 26° to 28°C. 

2. Flax thrives well with soil temperatures as low as 13°C. 

3. The critical temperature for the infection of fiax by Fusarium Lini 
is about 15°C. 

4. There is a close correlation between the temperatures at which Fusa- 
rium. Lini grows best in pure culture and those at which flax wilt is most 
destructive. 

University' of Wisconsin 
Madison, Wisconsin 

' Gilman, J. C. The relation of temperature to the infection of cabbage by 
Fusarium conglutinans Wollenw. Phytopath. 4: 404. 1914. 

— — Cabbage yellows and the relation of temperature to its occurrence. Ann. 
Missouri Bot. Gard. 3: 25-84. 1916. 



Plate XI. Relation of Temperature to the Growth op Fusarium Lini 

These culture plates (1.8 per cent potato agar) were inoculated with much care 
as to uniformity and then incubated for six days at different temperatures, as fol- 
lows: (1) 8.5-10°, (2) 11°, (3) 12-13°, (4) 14°, (5) 15°, (6) 16°, (7) 17°, (8) 19°, (9) 22° 
(10) 24-25°, (11) 25-26°, (12) 26-28°, (13) 29-30°, (14) 34°, (15) 37°. 



PHYTOPATHOLOGY. VII 




Tisdale: Relation of Temperature to Infection 



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